US5550332A - Loudspeaker assembly - Google Patents
Loudspeaker assembly Download PDFInfo
- Publication number
- US5550332A US5550332A US08/570,379 US57037995A US5550332A US 5550332 A US5550332 A US 5550332A US 57037995 A US57037995 A US 57037995A US 5550332 A US5550332 A US 5550332A
- Authority
- US
- United States
- Prior art keywords
- magnetic
- voice coil
- center plate
- magnets
- width
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
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Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R9/00—Transducers of moving-coil, moving-strip, or moving-wire type
- H04R9/02—Details
- H04R9/04—Construction, mounting, or centering of coil
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R9/00—Transducers of moving-coil, moving-strip, or moving-wire type
- H04R9/02—Details
- H04R9/025—Magnetic circuit
Definitions
- the present invention relates to a loudspeaker assembly in which a voice coil is driven by a magnetic field (hereinafter called repulsive magnetic field) generated by a magnetic circuit (hereinafter called repulsive magnetic circuit) having two magnets which are magnetized in the direction of thickness and the magnetic poles of the same polarity are faced with each other with a center plate being interposed therebetween.
- repulsive magnetic field a magnetic field generated by a magnetic circuit
- repulsive magnetic circuit having two magnets which are magnetized in the direction of thickness and the magnetic poles of the same polarity are faced with each other with a center plate being interposed therebetween.
- a conventional loudspeaker has the magnetic characteristics and the structure such as shown in FIGS. 5 and 6.
- FIG. 5 explains the magnetic flux distribution and the directions of lines of magnetic force, respectively of a magnetic circuit of a repulsive magnetic type loudspeaker.
- FIG. 6 is a cross sectional view showing the structure of a conventional loudspeaker.
- a repulsive magnetic circuit has been considered not suitable for driving a voice coil 1c of a loudspeaker of the type that the diaphragm is driven at a large vibration amplitude, because of the magnetic characteristics specific to this magnetic circuit.
- magnetic fluxes are guided from the magnetic poles of the same polarity (N pole) facing each other into a center plate P interposed between the two magnets M1 and M2, extend from the outer periphery of the center plate P, and immediately flow toward the opposite magnetic poles (S pole).
- the magnetic flux distribution of this magnetic circuit provides a pattern as in the following. Namely, the magnetic flux density at the voice coil is great near the center plate P, decreases at the positions higher and lower than the position of the center plate P, becomes "0" at the position approximately 1/3 to 1/2 of the thickness of each magnet, increases at the positions higher and lower than the "0" point position with the direction of magnetic fluxes being reversed, takes a negative side maximum value at the positions corresponding to the top and bottom surfaces of the two magnets, and decreases toward "0" as the positions become higher and lower from the maximum positions.
- the voice coil 1c vibrates in the upward and downward directions as viewed in FIG. 6 to drive a diaphragm 6 and produce sounds.
- a so-called long voice coil is used as shown in FIGS. 5 and 6 in order to improve the amplitude efficiency at the low frequency band.
- such a long voice coil 1c has a winding width about two to three times wider than the thickness of the center plate P or top plate T.
- the long voice coil 1c in the repulsive magnetic circuit receives the magnetic fluxes near at the center plate P at the central area of the coil. However, at the other area near at the top and bottom surfaces of the magnets, the voice coil 1c enters the negative side magnetic flux distribution region. Therefore, the total magnetic fluxes for driving the voice coil 1c decrease, lowering the sound pressure.
- a long voice coil As described above, as a voice coil for driving a woofer, a long voice coil has been conventionally used in order to improve the amplitude efficiency at the low frequency band. Generally, such a long voice coil has a winding width about two to three times wider than the thickness of the top plate.
- the long voice coil receives the magnetic fluxes near at the center plate P at the central area of the coil. However, at the other area near at the top and bottom surfaces of the magnets, the voice coil enters the negative side magnetic flux distribution region. Therefore, the total magnetic fluxes for driving the voice coil decrease, lowering the sound pressure.
- a loudspeaker assembly for driving a voice coil by a magnetic field generated by a magnetic circuit having two magnets which are magnetized in the direction of thickness and has the magnetic poles of the same polarity faced with each other with a center plate made of magnetic material being interposed therebetween, wherein the winding width of the voice coil is set equal to or greater than a width between two transition points of the magnetic flux distribution of the magnetic circuit from a positive side to a negative side.
- the winding width of the voice coil is preferably set less by 10% to 20% than the width between the two transition points.
- the winding width of a voice coil is set to equal to or greater than the width between two transition points of the magnetic flux distribution shown in FIG. 5. Therefore, an adverse effect of the negative side magnetic flux region hardly occurs even during the low frequency band reproduction when the voice coil is driven at a large amplitude.
- FIG. 1 is a cross section showing the structure of a loudspeaker according to an embodiment of the present invention.
- FIG. 2A is a broken perspective view partially in section showing the structure of a magnetic circuit according to the present invention
- FIG. 2B is a perspective view partially in section showing the structure of the magnetic circuit shown in FIG. 2A.
- FIGS. 3A to 3C are cross sections showing the main parts of voice coil driving units and the diagrams showing magnetic flux distributions of magnetic circuits, respectively of loudspeakers (1), (2), and (3).
- FIG. 4 is a graph comparing the characteristics of embodiment loudspeakers and a conventional loudspeaker.
- FIG. 5 illustrates the magnetic flux distribution and the direction of magnetic fluxes of a repulsive magnetic circuit.
- FIG. 6 is a cross section showing the structure of a conventional loudspeaker.
- Embodiments of a loudspeaker assembly according to the present invention will be described with reference to FIGS. 1 to 5. Like elements to those of a conventional loudspeaker are indicated by using identical reference representations, and the description thereof is omitted.
- FIG. 1 is a cross section showing the structure of a loudspeaker according to an embodiment of the present invention.
- FIG. 2A is a broken perspective view partially in section showing the structure of a magnetic circuit according to the present invention
- FIG. 2B is a perspective view partially in section showing the structure of the magnetic circuit.
- FIGS. 3A to 3C are cross sections of the main parts of voice coil driving units and the diagrams of magnetic flux distributions of magnetic circuits.
- the width of the voice coil is set less than the transition point width
- FIG. 3B the width is set equal to the transition point width
- FIG. 3C the width is set greater than the transition point width.
- FIG. 4 is a graph showing a comparison between embodiment loudspeakers and a conventional loudspeaker.
- Loudspeakers of the embodiments are 8-inch woofers with a repulsion magnetic circuit.
- magnets M1 and M2 are made of neodymium-based material, and of a ring shape having an outer diameter of 37.4 mm, an inner diameter of 15 mm, and a thickness of 9 mm.
- the magnets M1 and M2 were magnetized in the direction of thickness.
- An aluminum holder 4 shown in FIGS. 1, 2A, and 2B was formed to support the magnets M1 and M2, a center plate P, and an outer ring L.
- a cylindrical center guide 41 is formed upright at the central area of the bottom 44 of the holder 4.
- a step 42 is formed at the lower end of the center guide 41 to properly match the total thickness of the magnets M1 and M2 and center plate P.
- Acrylic adhesive agent is coated on the surface of the step 42.
- the magnet M2 is inserted into the center guide 41 through the inner diameter space M21 by directing the N pole upward.
- the outer diameter of the center guide 41 was set to 15.95 mm.
- Adhesive agent is coated on the upper surface of the inserted magnet M2.
- the center plate P is then fitted in the center guide 41 downward until the lower surface of the center plate P becomes in tight contact with the N pole surface of the magnet M2.
- the center plate P is made of ring iron having an outer diameter of 38.43 mm, an inner diameter of 15.95 mm, and a thickness of 6 mm. The edge portions at the inner diametrical periphery of the center plate P was beveled by C0.4.
- Adhesive agent is then coated on the upper surface of the fitted center plate P.
- the magnet M1 is inserted in the center guide 41 through the inner diameter space M11 by directing the N pole downward, until the magnet M1 becomes in tight contact with the upper surface of the center plate P.
- the magnets M1 and M2 with their N poles facing each other interpose the center plate P therebetween, and the center plate outer circumference P2 extends by about 0.5 mm outside of the outer circumferences M12 and M22 of the magnets M1 and M2.
- the outer ring L is then disposed outside of the center plate P to form a magnetic gap of 1.27 mm from the center plate P.
- the outer ring L is made of iron having an inner diameter of 40.97 mm, an outer diameter of 45 mm, and a height of 12 mm.
- the magnetic flux distribution near at this magnetic gap is shown in FIG. 3.
- Positive side magnetic fluxes of about 0.9 tesla distribute over the width generally corresponding to the thickness of the center plate P.
- Magnetic fluxes gradually decrease at the positions higher and lower than that of the center plate P.
- the magnetic flux density is "0" at the positions higher and lower by about 3 mm from the center plate P, i.e., at the positions about 1/3 the thickness of the magnet.
- the directions of magnetic fluxes become opposite to those near at the center plate P at the positions higher and lower than the "0" point.
- These negative side magnetic fluxes take a maximum value (-0.35 Tesla) at the positions corresponding to the top and bottom surfaces of the magnets.
- the magnetic fluxes gradually decrease to "0" value as the positions lower and rise from these maximum points.
- This magnetic circuit on the holder 4 is mounted on a frame 3.
- the holder 4 is formed with a flange 43 having a width of about 2 mm and a thickness of 3 mm.
- the flange 43 is formed with four projections 46 extending outward at positions different by 90 degrees in the radial direction. A tap of about 5 mm is formed in the central area of each projection 46.
- the holder 4 is attached to the bottom of the frame 3.
- a mounting hole having a diameter of 5.5 mm is formed in the bottom of the frame at the position corresponding to each tap 45.
- the magnetic circuit on the holder 4 is fixed to the frame 3 by using screws 5 as shown in FIG. 1.
- the frame 3 has an outer diameter of about 215 mm and a depth of about 30 mm, which is commonly called an 8-inch frame made of a pressed iron frame having a thickness of 1.2 mm.
- Voice coils 1 such as shown in FIGS. 3A to 3C are mounted on magnetic circuits.
- a voice coil 1a is wound on a bobbin 11 at its lower end portion.
- the bobbin 11 is made of an aluminum plate of 0.1 mm thickness.
- a coil wire is made of a copper wire of 0.21 mm diameter generally called 1PRESVW coated with insulating material.
- the winding width of the coil 1a is about 10 mm and resistance is 3.4 ohms.
- the voice coil 1a has a width less by 17% than the width d (about 12 mm) between the transition points A and B of the magnetic flux distribution of the repulsive magnetic circuit from the positive side to the negative side, i.e., between the magnetic flux 0 points A and B.
- Vibration system components including a diaphragm 6 and a damper 2 were mounted on the assembly of the magnetic circuit and frame 3 to complete a loudspeaker (1).
- the characteristic of this loudspeaker (1) was measured, the result being indicated by a solid line in FIG. 4.
- the diaphragm 6 is made of pulp and has a conical shape with an outer diameter of about 194 mm (including an edge), a neck diameter of 39.6 mm, and a depth of about 27.8 mm.
- the damper 2 is of a general type made of cotton cloth or the like impregnated with phenol and formed with corrugations.
- Another voice coil 1c has a d.c. resistance of 3.4 ohms same as the coil 1a, a different wire diameter, and a winding width d of about 16 mm which is greater than the width d between the transition points A and B.
- Another voice coil 1b has a winding width of 12 mm substantially the same as the width d between the transition points A and B.
- a loudspeaker (2) with the voice coil 1b and a loudspeaker (3) with the voice coil 1c were completed to measure the characteristics which are indicated by a fine one-dot-chain line and a fine broken line in FIG. 4.
- FIG. 6 Another loudspeaker (4) with a conventional general magnetic circuit shown in FIG. 6 different from the repulsive magnetic circuit was formed using a diaphragm 6 and damper 2 similar to those described above to measure the characteristics which are indicated by a thick broken line in FIG. 4.
- the york pole Y has a diameter of 38.43 mm
- the top plate T has a thickness of 6 mm and an inner diameter of 40.97 mm, to thereby provide a magnetic gap of 1.27 mm.
- the magnet size was determined to provide a magnetic flux density of about 0.9 tesla similar to the embodiment repulsive magnetic circuits.
- the long voice coil has a winding width of 16 mm.
- the loudspeaker (3) with the voice coil 1c having the winding width of about 16 mm has a sound pressure level lower by 3 dB than the loudspeaker (4) over the whole frequency band, posing a practical problem.
- the loudspeaker (1) with the voice coil 1a having the winding width less by about 17% than the width d between the transition points A and B poses no practical problem of a sound pressure at a low frequency band although the characteristics lower than a minimum resonance frequency differs slightly.
- the loudspeaker (2) with the voice coil 1b having the winding width of 12 mm substantially the same as the winding width d between the transition points A and B provides the characteristics sufficient for practical use although the sound pressure level lowers slightly as compared with the loudspeaker (4).
- the winding width of the voice coil less by 10 to 20% than the width d between the transition points A and B.
- the magnetic flux distribution of the embodiment magnetic circuit depends upon the cross sectional shapes of the magnets, center plate, and outer ring.
- the winding width of the voice coil is set preferably to that described above, because the magnetic flux distribution will not change basically where the magnetic flux density becomes "0" near at the positions 1/3 to 1/2 the thickness of the magnet, and increases to the negative side at the positions higher and lower than the "0" point.
- the winding width of the voice coil is set to that described above, for the loudspeaker of the type that the outer ring L made of soft magnetic material such as iron is not disposed outside of the center plate P, but soft magnetic material is used as the core or outer sheath of the wire of the voice coil.
- the transition points A and B are basically the same positions.
- the magnetic flux distribution of the repulsive magnetic circuit is symmetrical relative to the positions at the voice coil, i.e., relative to the direction of driving the voice coil, thereby providing a symmetrical drive force of the diaphragm. This is extremely advantageous over a conventional general magnetic circuit wherein the magnetic flux distribution is asymmetrical relative to the positions at the voice coil.
- the winding width of the voice coil used with the repulsive magnetic circuit By setting the winding width of the voice coil used with the repulsive magnetic circuit to the width substantially equal to or less than the width d between the transition points A and B, the adverse effect of the negative side magnetic flux region hardly occurs even during the low frequency reproduction where a woofer vibrates at a large amplitude, thereby providing the sound pressure characteristics such as indicated by the solid line (loudspeaker (1)) and by the one-dot-chain line (loudspeaker (2)) not so bad as compared with the conventional loudspeaker (1).
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- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Acoustics & Sound (AREA)
- Signal Processing (AREA)
- Audible-Bandwidth Dynamoelectric Transducers Other Than Pickups (AREA)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US08/570,379 US5550332A (en) | 1992-10-20 | 1995-12-11 | Loudspeaker assembly |
Applications Claiming Priority (5)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP4281321A JPH06133394A (ja) | 1992-10-20 | 1992-10-20 | スピーカの構造 |
JP4-281321 | 1992-10-20 | ||
US13597393A | 1993-10-14 | 1993-10-14 | |
US37046495A | 1995-01-09 | 1995-01-09 | |
US08/570,379 US5550332A (en) | 1992-10-20 | 1995-12-11 | Loudspeaker assembly |
Related Parent Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US37046495A Continuation | 1992-10-20 | 1995-01-09 |
Publications (1)
Publication Number | Publication Date |
---|---|
US5550332A true US5550332A (en) | 1996-08-27 |
Family
ID=17637479
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US08/570,379 Expired - Lifetime US5550332A (en) | 1992-10-20 | 1995-12-11 | Loudspeaker assembly |
Country Status (4)
Country | Link |
---|---|
US (1) | US5550332A (de) |
EP (2) | EP0595169A3 (de) |
JP (1) | JPH06133394A (de) |
DE (2) | DE595169T1 (de) |
Cited By (16)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5682436A (en) * | 1994-06-06 | 1997-10-28 | Kabushiki Kaisha Kenwood | Multipoint driving loudspeaker having repulsion magnetic-type driving unit |
US5715324A (en) * | 1994-01-05 | 1998-02-03 | Alpine Electronics, Inc. | Speaker having magnetic circuit |
US5856772A (en) * | 1994-01-21 | 1999-01-05 | Alliedsignal, Inc. | Low stress magnet interface |
US5878150A (en) * | 1994-03-28 | 1999-03-02 | Matsushita Electric Industrial Co., Ltd. | Damper for a loudspeaker and a method for producing the same |
US6343128B1 (en) | 1999-02-17 | 2002-01-29 | C. Ronald Coffin | Dual cone loudspeaker |
US6466676B2 (en) | 2000-02-09 | 2002-10-15 | C. Ronald Coffin | Compound driver for acoustical applications |
US20030133587A1 (en) * | 2002-01-16 | 2003-07-17 | Hyre David E. | Speaker driver |
US6639993B2 (en) | 2001-12-29 | 2003-10-28 | Alpine Electronics, Inc | Loudspeaker with low distortion and high output power |
US20060008367A1 (en) * | 2004-07-08 | 2006-01-12 | Mitsuo Yokozawa | Actuator and pump device |
US20060045305A1 (en) * | 2004-08-27 | 2006-03-02 | Naoki Shimamura | Speaker |
US20060239496A1 (en) * | 2005-04-25 | 2006-10-26 | Stiles Enrique M | Magnetically tapered air gap for electromagnetic transducer |
US20060251286A1 (en) * | 2005-04-13 | 2006-11-09 | Stiles Enrique M | Multi-gap air return motor for electromagnetic transducer |
US20070160257A1 (en) * | 2005-04-13 | 2007-07-12 | Stiles Enrique M | Axial magnet assisted radial magnet air return motor for electromagnetic transducer |
US20100215207A1 (en) * | 2007-12-03 | 2010-08-26 | Osamu Funahashi | Speaker |
US10051374B2 (en) * | 2016-04-15 | 2018-08-14 | Harman International Industries, Incorporated | Loudspeaker motor and suspension system |
USD964321S1 (en) | 2019-08-23 | 2022-09-20 | Tymphany Acoustic Technology Limited | Waveguide |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP4081842B2 (ja) * | 1998-03-11 | 2008-04-30 | ソニー株式会社 | スピーカ装置 |
GB2371165B (en) * | 2001-01-16 | 2004-12-22 | Kh Technology | Magnet system for loudspeakers |
CN106792402B (zh) * | 2017-03-18 | 2022-06-03 | 歌尔股份有限公司 | 动磁式扬声器 |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4783824A (en) * | 1984-10-23 | 1988-11-08 | Trio Kabushiki Kaisha | Speaker unit having two voice coils wound around a common coil bobbin |
US5142260A (en) * | 1991-03-08 | 1992-08-25 | Harman International Industries, Incorporated | Transducer motor assembly |
Family Cites Families (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3201529A (en) * | 1962-11-16 | 1965-08-17 | Philip C Surh | Dynamic speaker |
JPS59148500A (ja) * | 1983-02-14 | 1984-08-25 | Sony Corp | ダイナミツク形スピ−カ |
DE3730305C1 (de) * | 1987-09-10 | 1989-03-23 | Daimler Benz Ag | Lautsprecher |
JPH05122792A (ja) * | 1991-10-25 | 1993-05-18 | Matsushita Electric Ind Co Ltd | スピーカ |
-
1992
- 1992-10-20 JP JP4281321A patent/JPH06133394A/ja active Pending
-
1993
- 1993-10-19 EP EP93116900A patent/EP0595169A3/de not_active Withdrawn
- 1993-10-19 EP EP97112283A patent/EP0810813A3/de not_active Withdrawn
- 1993-10-19 DE DE0595169T patent/DE595169T1/de active Pending
- 1993-10-19 DE DE0810813T patent/DE810813T1/de active Pending
-
1995
- 1995-12-11 US US08/570,379 patent/US5550332A/en not_active Expired - Lifetime
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4783824A (en) * | 1984-10-23 | 1988-11-08 | Trio Kabushiki Kaisha | Speaker unit having two voice coils wound around a common coil bobbin |
US5142260A (en) * | 1991-03-08 | 1992-08-25 | Harman International Industries, Incorporated | Transducer motor assembly |
EP0503860A2 (de) * | 1991-03-08 | 1992-09-16 | Harman International Industries, Incorporated | Wandler-Motor-Anordnung |
Non-Patent Citations (3)
Title |
---|
Abstract of JP 59148500, Aug. 25, 1984. * |
Journal of the Audio Engineering Society, vol. 29, No. 1/2, Jan. 1981, New York, US, pp. 10 26, Mark R. Gander Moving Coil Loudspeaker Topology as an Indicator of Linear Excursion Capability . * |
Journal of the Audio Engineering Society, vol. 29, No. 1/2, Jan. 1981, New York, US, pp. 10-26, Mark R. Gander "Moving-Coil Loudspeaker Topology as an Indicator of Linear Excursion Capability". |
Cited By (23)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5715324A (en) * | 1994-01-05 | 1998-02-03 | Alpine Electronics, Inc. | Speaker having magnetic circuit |
US5856772A (en) * | 1994-01-21 | 1999-01-05 | Alliedsignal, Inc. | Low stress magnet interface |
US5878150A (en) * | 1994-03-28 | 1999-03-02 | Matsushita Electric Industrial Co., Ltd. | Damper for a loudspeaker and a method for producing the same |
US5966797A (en) * | 1994-03-28 | 1999-10-19 | Matsushita Electric Industrial Co., Ltd. | Method of manufacturing a damper for a loudspeaker |
US5682436A (en) * | 1994-06-06 | 1997-10-28 | Kabushiki Kaisha Kenwood | Multipoint driving loudspeaker having repulsion magnetic-type driving unit |
US6343128B1 (en) | 1999-02-17 | 2002-01-29 | C. Ronald Coffin | Dual cone loudspeaker |
US6466676B2 (en) | 2000-02-09 | 2002-10-15 | C. Ronald Coffin | Compound driver for acoustical applications |
US6639993B2 (en) | 2001-12-29 | 2003-10-28 | Alpine Electronics, Inc | Loudspeaker with low distortion and high output power |
US7039213B2 (en) | 2002-01-16 | 2006-05-02 | Hyre David E | Speaker driver |
US20030133587A1 (en) * | 2002-01-16 | 2003-07-17 | Hyre David E. | Speaker driver |
US20060008367A1 (en) * | 2004-07-08 | 2006-01-12 | Mitsuo Yokozawa | Actuator and pump device |
US20060045305A1 (en) * | 2004-08-27 | 2006-03-02 | Naoki Shimamura | Speaker |
US7433487B2 (en) * | 2004-08-27 | 2008-10-07 | Alpine Electronics, Inc. | Speaker |
US20060251286A1 (en) * | 2005-04-13 | 2006-11-09 | Stiles Enrique M | Multi-gap air return motor for electromagnetic transducer |
US20070160257A1 (en) * | 2005-04-13 | 2007-07-12 | Stiles Enrique M | Axial magnet assisted radial magnet air return motor for electromagnetic transducer |
US20060239496A1 (en) * | 2005-04-25 | 2006-10-26 | Stiles Enrique M | Magnetically tapered air gap for electromagnetic transducer |
US20100215207A1 (en) * | 2007-12-03 | 2010-08-26 | Osamu Funahashi | Speaker |
US8351642B2 (en) * | 2007-12-03 | 2013-01-08 | Panasonic Corporation | Speaker |
US10051374B2 (en) * | 2016-04-15 | 2018-08-14 | Harman International Industries, Incorporated | Loudspeaker motor and suspension system |
USD964321S1 (en) | 2019-08-23 | 2022-09-20 | Tymphany Acoustic Technology Limited | Waveguide |
USD966235S1 (en) * | 2019-08-23 | 2022-10-11 | Tymphany Acoustic Technology Limited | Waveguide |
USD977457S1 (en) | 2019-08-23 | 2023-02-07 | Tymphany Acoustic Technology Limited | Waveguide |
USD986857S1 (en) | 2019-08-23 | 2023-05-23 | Tymphany Acoustic Technology Limited | Waveguide |
Also Published As
Publication number | Publication date |
---|---|
EP0810813A3 (de) | 1998-01-21 |
EP0810813A2 (de) | 1997-12-03 |
DE595169T1 (de) | 1994-11-17 |
JPH06133394A (ja) | 1994-05-13 |
EP0595169A2 (de) | 1994-05-04 |
DE810813T1 (de) | 1998-05-28 |
EP0595169A3 (de) | 1995-01-11 |
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